Organizers have lined up the requisite sound permits, so this will be a full-on amplified stage show&30151;no human-mic necessary.

"This is a really great way for people to rally around something that's nonviolent," said one of the organizers, who goes by the name Goldi. "It's something that diffuses tension and is really celebratory. As someone said in one of our recent meetings, 'You can't arrest a song.'"

The Union Square phase of the day's actions are mostly under the control of Occupy Wall Street's union and immigrant-advocacy allies, so organizers are emphasizing that the free concerts that afternoon are expected to be safe, family friendly, and low-risk for audience members who might be undocumented or otherwise wary of risking arrest.

Occupy Wall Street organizers are still in talks to bring in big-name performers for a later phase of the day's activities down on Wall Street. We'll bring you updates as those plans are confirmed.